Behavioral functions of forebrain catecholamine terminals are being investigated by studying the behavior of rats that have lost catecholamine terminals in certain regions of the forebrain. The catecholamine loss is produced by microinjections of 6-hydroxydopamine. At the present time we are attempting to define what forebrain catecholamine terminal fields are critical for exploratory behavior. We are determining the catecholamine loss by processing brains with the glyoxylic acid histofluorescence technique. BIBLIOGRAPHIC REFERENCE: Fink, J.S. and Smith, G.P. Correlation of pattern of catecholamine denervation and behavioral defects after intrahypothalamic 6-hydroxydopamine. Neuroscience Abstracts 1:406, 1975. Smith, G.P., Levin, B.E. and Erwin, G.N. Loss of active avoidance responding after lateral hypothalamic injections of 6-hydroxydopamine. Brain Res. 88: 483-498, 1975.